Water-soluble polymers containing pendent sulfonate groups have found wide utility as dispersants, scale and corrosion-preventing agents, detergent builders, sequestering agents, suspending agents, flame retardants, and the like. Polymers containing sulfonate groups are commonly prepared by polymerization of unsaturated sulfonate salt monomers. Carboxylate groups may be introduced into such polymers by copolymerizing an unsaturated dicarboxylic acid, acid salt, or anhydride with the unsaturated sulfonate salt. Copolymers of this type are described, for example, in Jpn. Kokai 149,705/75, 213,714/84, and 50064/79 and in European Pat. No. 353,817.
The usefulness of such copolymers as dispersants and the like is significantly affected by characteristics such as monomer composition, structure, and molecular weight. Therefore, it would be highly desirable to obtain sulfonate copolymers wherein the comonomer is an .alpha.,.beta.-unsaturated dicarboxylic acid imide so that copolymer properties may be varied as required to suit particular end-use applications.